1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device in which a mold resin is formed in a gap between substrates.
2. Description of the Related Art
With the development of electronic devices reduced in size and improved in multifunctionality, semiconductor devices of a Chip on Chip (CoC) type in which a plurality of semiconductor chips having through electrodes are stacked have been proposed. In a CoC semiconductor device, a mold resin is ordinarily provided between semiconductor chips. JP2007-36184A discloses a CoC semiconductor device and a method of manufacturing the CoC semiconductor device.
JP2007-36184A also discloses joining a plurality of chips through bump electrodes and injecting a mold resin in liquid form into gaps between the chips. In ordinary cases, a mold resin is injected from a side of each of semiconductor chips into gaps between the semiconductor chips by a liquid discharge method.
For example, when a mold resin is injected into a gap between substrates such as those of semiconductor chips, there is a possibility of a region where a mold resin, e.g., an underfill material or the like is not formed, i.e., a void, being formed in the gap between the substrates. This is due to the occurrence of a difference in flow velocity of the mold resin between a region where bump electrodes exist and a region where no bump electrodes exist. The mold resin flows fast downstream in a region where no bump electrodes exist, and enters in a roundabout fashion a region downstream of the region where the bump electrodes exist. Due to such a flow of the mold resin in a roundabout fashion, a space surrounded by the mold resin, i.e., a void, occurs in the vicinity of the region where the bump electrodes exist.
In particular, if the pitch between the bump electrodes is reduced, variation in flow velocity of the mold resin is increased and the possibility of occurrence of a void is increased.
When treatment after filling the gaps between the substrates with the mold resin, e.g., a treatment for thermally setting the mold resin is performed, stress is caused in the substrates by thermal expansion and thermal contraction. The above-described void reduces the durability under thermal stress in the vicinity of joints of the bump electrodes. There is, therefore, a possibility of breakage of the bump electrodes and, hence, a reduction in reliability of the semiconductor device.
Therefore, there is a demand for providing a semiconductor device manufacturing method capable of reducing the occurrence of a void between substrates.